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Good morning
I have recently purchased a 2016 Orbea Loki which I run 27.5 plus I don't do jumps or anything crazy it is mainly for a nice comfy long pootle at a nice pace as I am in no rush to get back to the bag of wind known as my other half !!
My problem is the frame should come with a 120mm fork and their specs say 531mm axle to crown but I am running some Manitou Machete 140mm axle to crown 551mm
Will I burst into flames and die screaming or is it ok to carry on riding it ? Only been out once and it felt absolutely spot on ,the frame only cost £100 so a crack wouldn't bother me however the fact I might go tarmac surfing on my face does
I suppose I am just wanting confirmation I am ok to carry on
Cheers
I've done it on a couple of bikes in the past (Including 140mm forks on a xc frame designed for 80mm) and still here to tell the tale, but YMMV
In my very limited forum-browsing experience, the 'risk' of running a too-long fork is vastly overstated. For the majority of people it'll be perfectly safe, especially if you're only bimbling.
There's a bigger chance of upsetting the handling of your bike. Making a bike too high at the front / too slack / too high at the BB is a thing.
If it rides OK I'd carry on and stop worrying. But you can make your own mind up 🙂
I've overforked pretty much every bike I've ever owned and it's always been an improvement.
The idea that a longer fork will overstress the headtube and the frame will break is nonsense. A 20mm increase on a 500mm AC length is 4%. That's utterly insignificant. It's the difference between riding naked and carrying a couple of litres of water, enough food for a full day's riding, and some extra clothing. Frames don't just snap because of a 4% increase in stress.
What will cause a frame to snap is taking a lightweight XC frame, putting a big fork on it, and riding like a DH monster. If you ride the bike the way it was designed to be ridden, you'll be fine.
Thanks everyone I'll carry on as is and probably save myself about £300 !!!
If it worries you then the machetes are internally adjustable with spacers. You could space then down to 120mm.
No. It’ll be fine
Are wider stantioned forks less prone to bushing wearing nowadays. Back when they were 30mm I'd put a 5" fork on a 4" hardcore hardtail and need to rebush twice a year when they start knocking.
The idea that a longer fork will overstress the headtube and the frame will break is nonsense. A 20mm increase on a 500mm AC length is 4%. That’s utterly insignificant.
It's even less than that, really, as the moment arm includes the wheel radius (ie distance from bottom headset bearing to tyre contact patch). So on a 29er, add another 14.5" (370mm):
20/(500+370) = 2.3%
As the man says, utterly insignificant.
I suspect that manufacturers' warnings against over-forking is more because it's an indication that the rider may be using the bike inappropriately. I have some sympathy with them from a warranty standpoint, but even so you'd have to be *really* overdoing it to exceed the design safety factors.